Plural rate burner apparatus

ABSTRACT

An aerated burner employs a mixing tube having a grid at an exit end for retaining a low rate flame impinging upon a flame sensing element and a deflecting member spaced from the exit end of the tubular member for deflecting a portion of a high rate flame against the flame sensing element.

United States Patent [191 Morris Apr. 9, 1974 [54] PLURAL RATE BURNER APPARATUS 3.162.238 12/1964 Claywell et al. 43l/346 X [75] Inventor: Mmns, Garden Grove 3,684,424 8/1972 Zink et al. 431/353 x Callf- 3.754.853 8/1973 Braucksiek et ai. 431/285 [73] Assignee: Robertshaw Controls Company,

Richmond Primary Examiner-Edward G. Favors [22] Filed: June 8, 1973 Altorney; Agent, or FirmAnthony A. OBrien [2i] Appl. No.1 368,542

- [57] ABSTRACT [52] US. Cl 431/353, 431/80, 431/346,

431/347 An aerated burner employs a mixing tube having a [5]] Int. Cl. F23d 15/02 grid at-an exit end for retaining a low rate flame [58] Field of Search 431/346, 347, 349, 353, pinging upon a flame Sensing element and a deflecting 431/284 285 member spaced from the exit end of the tubular member for deflecting a portion of a high rate flame [56] References C'ted against the flame sensing element.

UNITED STATES PATENTS 2,817.696 12/1957 Beck .1 43 N80 X 8 Claims, 4 Drawing Figures PATENTEUAPR 9 m4 3802' 829 SHEET 2 BF 2 PLURAL RATE BURNER APPARATUS BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to burner apparatus, and in particular, to burner apparatus employing flame sensing elements and which are operably at more than one rate.

2. Description of the Prior Art The prior art is exemplified by US. Pat. No. 3,586,242, No. 3,586,241, No. 3,516,773, No. 3,405,999, No. 2,581,590, No. 2,155,339, No. 2,073,448, No. 1,961,751, No. 1,818,471, and 810,968 and by Bunsen burner types such as that disclosed in service instructions from Dometic Sales Corporation, 2900 W. Mishawaka Road Elkhart, Indiana, USA, Edition 1. Publication No. 3803-E-Service, February, 1970 on page 51. Some of the prior art burners are 6;)- erable at more than one rate and some employ flame sensing elements; however, the requirements for a single burner apparatus operable both at a high input rate and at a standby rate for smaller heating appliances, such as small water heaters used in recreational vehicles, have not been entirely satisfied by the prior art.

SUMMARY OF THE INVENTION The invention is summarized in that a burner apparatus operable both at a high rate and at a low rate includes an orifice member having an orifice for projecting a stream of gaseous fuel from a supply'passageway, a tubular mixing member having one end adjacent the orifice member and adapted to receive a projected stream of fuel from the orifice, said mixing member having an opening adjacent to the orifice member for allowing passage of air for entrainment in a-stream of fuel from the orifice, a grid member over the other end of the mixing member, said g'rid member having a grid size sufficiently small to retain a flame and minimize flash back at the low rate of operation but sufficiently large to allow substantially free flow of gas at the high rate of operation, a flame sensing element mounted at a position laterally offset from the mixing member adjacent the other end of the mixing member :in the path of a low rate flame, and a deflecting member disposed in a spaced position in front of the other end of the mixing of an appliance illustrating a burner apparatus in accordance with the invention operating at a low rate.

FIG. 2 is a view similar to FIG. 1 but with portions of the burner apparatus shown in cross section and illustrating a high rate of operation.

FIG. 3 is an cross sectional elevation view of a modified burner structure portion of the burner apparatus shownin FIGS. 1 and 2.

FIG. 4 is a right side view of the burner structure portion of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT As illustrated in FIG. 1, the invention is embodied in an appliance employing a burner apparatus including a burner structure indicated generally at 10, a flame sensing element 12 and a tubular fire box or heat exchanger 14. The burner assembly 10 is connected to a gas supply conduit 16 having a supply passageway 18 communicating with a suitable plural rate fuel control device (not shown). One example of a suitable fuel control device is the plural rate fuel control device disclosed in US. Pat. application Ser. No. 98,246 by Jay R. Katchka and Henry C. Braucksiek filed Dec. 15, 1970.

The flame sensing element 12 is any suitable thermoresponsive device, such as a thermocouple, which can be used to operate facilities, such as a magnetic safety valve (not shown), to prevent release of hazardous gas in the event that the flame of the burner is extinguished by air drafts, loss of fuel or the like.

- The burner structure 10 and the flame sensing element 12 are mounted on a support 22 which is secured to a bracket 24 mounted in the heat exchanger 14. As illustrated in FIG. 2, the support 22 has a nipple 26 formed therein with an inwardly tapered end 28 and an inner threaded portion 30 which mates with an externally threaded fitting member 32 surrounding the supmember for deflecting a portion of a flame at the high rate of operation toward the flame sensing element.

An object of the invention is to construct a burner apparatus operable at both high and low rates suitable for use in small appliances.

It is also an object of the invention is to provide a plural rate burner suitable for appliances which can operate in a system employing propane.

An advantage of the invention is that it is especially effective in a tubular fire box or heat exchanger.

Additional features of the invention'include the pro vision of a disc spaced in front of a tubular mixing member such'that at a high ratcflames are retained adjacent the periphery of the disc; the provision-'ofa tubular heat exchanger having an interior surface upon which high rate flames impinge; and the provision of projections extending from sides of the exit ofa mixing member toward a disc in front of the exit.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a elevation view of a'broken away portion ply conduit 16. The fitting member 32 secures a flared end 34 of the conduit 16, an annular ferrule 36 and a flared end 38 of an orifice member 40 together between the forward end of the fitting member 32 and an inner surface of the tapered end 28 of the nipple 26. The annular ferrule 36'has the shape of an annulus generated by orbiting a triangle and is designed to mate between the flared ends 34 and 38.

The orifice member 40 has an orifice 42 for projecting fuel from the supply passageway 18 into atubular air and fuel mixing member 44 which is suitably secured at a rear or left end to the outsidecircumference of the nipple 26 and extends forward or to the right "over the orifice member 40. Preferably, the orifice 42 is some type of turbulator orifice, such as an orifice with internal or external tabs, non-round holes, etc. The tubular mixing member 44 has a plurality of circumferentially spaced openings or slots 46 disposed generally around or adjacent the'oriflce member 40 for allowing passage of air into the mixing member 44. The forward or rightend or exit of the mixing member 44 A deflecting member or disc 54 bent from a leg portion 56 which has a tab 58 secured to the tubular member 44 is disposed in front of the forward end of the -tubular member 44. The disc 54 is perpendicular to the tubular member 44 and has a diameter which is about equal to or approximately the diameter of the tubular member 44. The spacing of the disc 54 from the grid member 48 is such that at a high rate.of operation it acts as a flame retainer and a flame spreader and at a low rate of operation allows a flame to extend upward from the grid member 48.

The upper end of the supporting member 22 has a rearward portion 62 and a forward portion 64 with respective aligned bores therein for receiving the flame sensing element 12. A spring gripping device 66 is mounted within the bore in the forward portion 64 for securing the flame sensing element 12 in a position laterally offset from the'tubular member such that the element 12 extends above the forward end of. the tubular member 44 in the pathof a low rate flame.

} The tubular fire box 14 has a diameter such that high rate flames impinge upon the interior surface thereof.

The orifice member 40, the tubular mixing member 44, the tubular heat exchanger 14 and the disc 54 are illustrated as all being coaxial about a horizontal axis. However, the axis need not be horizontal; for example, the axis can extend at an angle from the horizontal wherein the angle is notso great as to prevent an upward extending flame at a low rate from impinging on the element 12. Also, the orifice member 40, the tubular mixing member 44, the tubular heat exchanger 14 and the disc 54 need not be coaxial.

' Operation of the apparatus at low and high rates is illustrated in respective FlGS. 1 and 2. Pressurized gaseous fuel supplied to the supply passageway 18 in the conduit 16 passes through the orifice member 40 where it exits from the orifice 42 into the tubular mixing member 44. The fuel is projected toward the forward end of the mixing member'44 and air drawn into the tubular mixing member 44 through slots 46 is mixed with the projected fuel. The mixture of air and fuel exits through the forward end of the tubular member 44 through the grid member 48 to sustain flames at both the high and low rates.

At the low rate the fuel supplied to the supply passageway 18 is at a relatively low pressure so that the velocityof the mixture of fuel and air passing through the grid member 48 is relatively low and an upward extending flame is generated from the grid member 48 impinging upon the flame sensing element 12. The grid member 48 retains the flame and prevents flash back of .the flame into the mixing member 44.

At the high rate of operation the fuel supplied to the passageway 18 is at a relatively higher pressure to generate a higher velocity of the mixture of fuel and air passing through the grid member 48 in the forward end of the tubular member 44. The high velocity mixture fuel and air is deflected into outward flaring directions by the disc 54. Flames sustained by fuel at the high rate leave the grid member 48 and are retained adjacent the periphery of the disc 54 by the spacing of disc 54 from the forward end of the tubular member 44 and grid member 48. The flames impinge against the inner surface of theheat exchanger 14 to form a generally hemispherical flame pattern which is very effective in respect to heat transfer in the tubular heat exchanger 14. An initial portion of upward directed flames at the high rate impinge upon the flame sensing element 12 to maintain the flame sensing element 12 in its operated condition.

The burner apparatus is particularly advantageous in that it can be employed in smaller heating and water heating appliances such as those used in recreation vehicles. In such applications, it is desirable to have burners operating at a full rate in the range of 8,000 to 12,000 Btu per hour and at a standby rate of about 200 Btu per hour on propane gas. At both the high rate and the low rate the flames are directed onto the flame sensing element which is positioned offset from the main axis of the burner; thus allowing the elimination of separate pilot burners and their tubing.

FIGS. 3 and 4 illustrate a modification of the burner strucute shown in FIGS. 1 and 2. Parts of the modified burner structure have the same numerals as the em-' bodiment shown in FIGS. 1 and 2 illustrating that such commonly numerated parts have similar structure and /or function. The modification has a supporting member 103 secured, such as by welding, to the upper portion of the supporting member 22. The supporting member 103 has a ring portion l05with an inwardly formed lip 107 on the forward edge thereof securing the grid 48 to the forward end of the tubular mixing member 44 which is also secured by the ring portion 105 and lip 107 over the outside circumference of the nipple 26. A plurality of circumferentially spaced projections 109 are secured to the outer periphery of the ring portion 105 to extend forward parallel from the forward end of the tubular mixing chamber 44. As illustrated in FIG. 4 the projections 109 are absent from the upper most are of the ring portion 105.

In operation of the modified burner apparatus at a high rate, the projections 109 further enhance the flame retaining and spreading properties of the disc 54 while not interfering with a low rate flame extending grom the grid member 48.

Since many modifications, variations and changes in detail can be made to the present embodiments, it is intended that all'matter in the foregoing description and shown in the-accompany drawings interpreted as illustrative and not in a limiting sense.

What is claimed is:

l. A burner apparatus operable both at a high ate and at a low rate comprising i an orifice member having an orifice for projecting a stream of gaseous fuel from a supply passageway,

a tubular mixing member having one end adjacent the orifice member and adapted toreceive a projected stream of fuel from the orifice, said mixing member having an opening adjacent the orifice member for allowing passage of air for entrainment in a stream of fuel from the orifice,

a grid member over the other end of the mixing member, said grid member having a grid size sufficiently small'to retain a flame and minimize flash back at the low rate of operation but sufficiently large to allow substantially free flow of gas at the high rate of operation,

a flame sensing element mounted at a position laterally offset from the mixing member adjacent the other end of the mixing member in the path of a low rate flame, and

a deflecting member disposed in a spaced position in the mixing member extends in a direction which is at least partially in a horizontal direction, and

the flame sensing element is mounted above the other end of the mixing member.

3. A burner apparatus as' claimed in claim 1 wherein the deflecting member is a disc mounted transverse to and intersecting an axis extending centrally through the mixing member.

4. A burner apparatus as claimed in claim 3 wherein the grid member and the disc are perpendicular to the axis of the mixing member. I

5. A burner apparatus as claimed in claim 3 wherein the disc is spaced from the grid such that at a low rate a flame is retained by the grid member and at a high rate a flame is retained adjacent the periphery of the disc.

6. A burner apparatus as claimed in claim 1 wherein there is included a tubular fire box, and

means for mounting the mixing member and flame sensing element longitudinally within the tubular fire box.

7. A burner apparatus operably both at a high rate and at a low rate comprising an orifice member having a orifice for projecting a stream of gaseous fuel;

means for connecting the orifice member to a supply conduit;

a tubular mixing member having a horizontal axis and one end adjacent the orifice member;

said mixing member adapted to receive a projected stream of fuel from the orifice and having an opening adjacent the orifice vmember for allowing passage of air for entrainment in a stream of fuel from the orifice;

agrid member mounted perpendicular to the axis of the mixing member over the other end of the mixing member;

said grid member having a grid size sufficiently small to retain a flame and minimize flash back at the low rate of operation but sufficiently large to allow substantially free flow of gas at the high rate of operation;

a flame sensing element positioned above the other end of the mixing member,

a tubular fire box extending coaxially along the axis of the mixing member;

means for mounting the orifice member, the mixing member and the flame sensing element within the fire box;

a disc coaxial and perpendicular to theaxis of the mixing member;

said disc having a diameter which is about equal to the diameter of the mixing member;

means for mounting the disc spaced in frontof the other opening of the tubular member such that a low rate flame extends upward from the grid member impinging upon the flame sensing element and a high rate flame extends radially outward from adjacent the periphery of the disc impinging upon the flame sensing element; and

said tubular fire box having a diameter such that a high rate flame impinges upon the interior surface thereof.

8. A burner apparatus as defined in claim 7 wherein, 

1. A burner apparatus operable both at a high rate and at a low rate comprising an orifice member having an orifice for projecting a stream of gaseous fuel from a supply passageway, a tubular mixing member having one end adjacent the orifice member and adapted to receive a projected stream of fuel from the orifice, said mixing member having an opening adjacent the orifice member for allowing passage of air for entrainment in a stream of fuel from the orifice, a grid member over the other end of the mixing member, said grid member having a grid size sufficiently small to retain a flame and minimize flash back at the low rate of operation but sufficiently large to allow substantially free flow of gas at the high rate of operation, a flame sensing element mounted at a position laterally offset from the mixing member adjacent the other end of the mixing member in the path of a low rate flame, and a deflecting member disposed in a spaced position in front of the other end of the mixing member for deflecting a portion of a flame at the high rate of operation toward the flame sensing element.
 2. A burner apparatus as claimed in claim 1 wherein the mixing member extends in a direction which is at least partially in a horizontal direction, and the flame sensing element is mounted above the other end of the mixing member.
 3. A burner apparatus as claimed in claim 1 wherein the deflecting member is a disc mounted transverse to and intersecting an axis extending centrally through the mixing member.
 4. A burner apparatus as claimed in claim 3 wherein the grid member and the disc are perpendicular to the axis of the mixing member.
 5. A burner apparatus as claimed in claim 3 wherein the disc is spaced from the grid such that at a low rate a flame is retained by the grid member and at a high rate a flame is retained adjacent the periphery of the disc.
 6. A burner apparatus as claimed in claim 1 wherein there is included a tubular fire box, and means for mounting the mixing member and flame sensing element longitudinally within the tubular fire box.
 7. A burner apparatus operably both at a high rate and at a low rate comprising an orifice member having a orifice for projecting a stream of gaseous fuel; means for connecting the orifice member to a supply conduit; a tubular mixing member having a horizontal axis and one end adjacent the orifice member; said mixing member adapted to receive a projected stream of fuel from the orifice and having an opening adjacent the orifice member for allowing passage of air for entrainment in a stream of fuel from the orifice; a grid member mounted perpendicular to the axis of the mixing member over the other end of the mixing member; said grid member having a Grid size sufficiently small to retain a flame and minimize flash back at the low rate of operation but sufficiently large to allow substantially free flow of gas at the high rate of operation; a flame sensing element positioned above the other end of the mixing member, a tubular fire box extending coaxially along the axis of the mixing member; means for mounting the orifice member, the mixing member and the flame sensing element within the fire box; a disc coaxial and perpendicular to the axis of the mixing member; said disc having a diameter which is about equal to the diameter of the mixing member; means for mounting the disc spaced in front of the other opening of the tubular member such that a low rate flame extends upward from the grid member impinging upon the flame sensing element and a high rate flame extends radially outward from adjacent the periphery of the disc impinging upon the flame sensing element; and said tubular fire box having a diameter such that a high rate flame impinges upon the interior surface thereof.
 8. A burner apparatus as defined in claim 7 wherein, there is included a plurality of projections extending from side portions of the mixing member parallel to the axis of the mixing member toward the disc. 